Magnetic speedometer



A, C. WOOD.

MAGNEnc sPEEnoMETER.

APPLICATION FIITED OCT. 16. 1920. K

Patented May 9,v A1922.

NVENTOR H Wren@ C Waal mA TTREE Y6? WITNESS! one of the ball bearings,

UNITED STATES? PATENT OFFICE.

ANDREW C. WOOD, OF CHICAGO, 1' L`.l'.l'.N'OIS, ASSIGNOR T0 STEWART-WARNER SPEEDOMETER CORPORATION, OF CHICAGO. ILLINOIS, A CORPORATION OF VIRGINIA.

MAGNETIC SPEEDOMETER.

Specification of Letters Patent.

Patented May 9,1922.

Application med october 1e, 1920. serial No. 417,448.

To all ltoko/m it mol/'y concern:

Be it known that I, ANDREW C. lVoop,

a citizen of the United States, and a res1' dent of' the cit of Chicago, in the county of Cook and the ta'te of lllinois,have invented certain new and useful Improvements in Magnetic Speedometers, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof.

The purpose of this invention is to provide an improved construction ofl magnetic speedometer, the means for compensating for temperature changes and compactness of construction. lt consists in the elements and features ofconstruction shown and described,

as indicated in the claims.

ln the drawingsz- Figure l is a section axial with respect to the rotor of a speedometer embodying this invention through the portion of the case containing the same.

Figure 2 is a top plan view of the structure shown in Figure 1.- v

Figure 3 is a section at the line, 3 3, on Figure 2.

A is the casing of the instrument in which the speedometer mechanism isy contained, the same being made of either magnetic or non-magnetic material and having an interiorly projecting bored for receiving spaced apart along the axis of the bore, ball bearings, l', l, for the shaft, 2, of a rotor for carrying the magnet, as hereinafter more particularly describe The shaft, 2, is reducedin diameter from one end to form a tapered journal at QPfor and at the extreme end to afford a cylindrical seat, 9,,lfor the adjustable or wear-compensating cone jour-V nal member, 2, Intermediatethetwo ball bearings, this shaft carries rigidly, and preferably. formed integrally with it, a gear member, 3, which in the structure shown a worm gear for meshing with a worm, 4, ona drive shaft, 5, for which the mount, A1, has an aperture, al, transverse to the axial aperture, a, and opening laterally into said axial aperture for the intermeshing of the'worm and the gear. The rotor shaft, 2, is hollow from end to end for permitting the' extension through it of the spindle, 6, of the nonmagnetic drag member, 7 hereinafter particularly with respect to mount, A1, axially.v

more particularly described. And the adjusting screw, 8, by which through the interposing spring washer, 8, the compensat ing cone member, 2, is adjusted on the reduced cylindrical part 2", of the shaft, 2, is axially apertured to permit-the spindle, 6, to extend through it, and reach a step bearing, l0, which is mounted -in a cover plate, 11, which encloses the enlargement or counterbore, 10a, of the axial aperture, a, of the mount, ,said counterbore being necessary to admit the rear or bottom ballbearing, and accommodate the compensating cone and its adjustment. rl`he shaft, 2, carries rigidly the magnet mount, l2, which is of non-magnetic 'material and has rigidly mounted upon it a split ring magnet, 13, and also by securement to the end of flat face of the mount, the field-deiiecting member, 15, which is arcuate in form and extends from the point of its mounting by means of the securing screws, 16, in an arc corresponding approximately to the magnet path of rotation, and substantially parallel to the face of the magnet,that is, in a plane at right angles to the axis,to a point opposite the magnet gap slightly beyond which it extends. rl`his field-deflecting member is constructed also for serving the purpose of a te'mperature-compensating device, and is for that purpose bimetallic, consisting of two lamin of metals having different coefficients of expansion under temperature chan-ge, one being magnetic, the metal having the higher co-efficient being on the side away from the magnet, so that upon rise of temperature, the field deflector tends to become flexed concave toward the magnet so that its free end moves toward the magnet, thereby increasing its effect for deflecting the lines of force of the magnetic field, and increasing the number of said lines which are cut by the drag member, 7. rEhe drag member, 7, is adisk carried bymeans of a graduated cup, 7x, whose outer wall has the graduations for speed indications exposed for reading Vthrough the side opening, X, of the casing, and whose bottom is secured fast at the center to the spindle, 6, for oscillating in a plane parallel to the plane of rotation of the magnet between the side of the magnet and the field deflector hereinafter mentioned. As a convenient means of securing the drag disk to the cup, TX, said disk is made cupped or i flanged as shown, and dimensioned for makthe check ring, 30, screwed intothe upper Thematerial of all of' upon said drag member.

lng a pressed or drive fit within the graduated'lan e of the cup, 7*.

.The lied deflector, 15, is resilient and normally shaped so that it trends slightly away from the plane of the upper end of the mount, 12, to which it is and at the short distance from its point of engaging outside the member, 15, so that y screwing said screw inward more or less after the head comes into contact with the outer surfaces of said delector, 15, said member is spruno'. toward the magnet pole at its free end. he original deflection of said member, 15, from a true plane is such as to cause its free end to standoff from the magnet somewhat more than the maxi mum distance by which Vit should be separated from the magnet in order to produce the necessary deflection of the field; and/by setting the screw in more or less this distance may be varied to calibrate as is necessary in view of the unavoidable variation in the strength of different magnets.

25 is a hair spring preferably of non-magnetic material, as bronze, connected at one end to an arm, 26, mounted on the case, and on the other end to a spindle, 6, of the drag member, operating in the usual manner for resisting the drag of the rotating magnet Said arm, 26, af fords bearing for the upper endof the spindle, 6, and there is preferably-provided `a spring stop linger, 27, for checking the upper end of the spindle, causing its lower end to remain seated in the'step bearing formed by a jewel, 29, mounted in the bearing'memer, 10, -above mentioned, and secured by end of said bearing. the parts not specifically described as magnetic or non-magnetic may be any material suitable for the mechanical service required. claim l. In a magnetic speedometer, in combination with 'a rotor, a magnet device mounted thereon for rotation in a pl'anegcontainingY all the magnet poles; a lieId-deflecting member carriedl by the rotor extending opposite he ma etic gap; a drag memberpivoted for osclllation about` theaxis of the rotor,

extending in the .plane of its oscillation d ,transversely of the secured at one end, v

`tion awayfrom 'the magnet proximate to the magnet and to the fielddeflecting member; a carrier :for the drag member which extends from the pivot spinv dle ofthe latter radially past the outer margin of the lield-delecting member and thence plane of rotation of said the latter thereto.

In a magnetic speedometer, in combinaa magnet device mounted proximate to the magnet and to the field de fleeting member, said iield-dellecting member being temperature-responsive for causing its movement toward and from the magnet under changes of temperature.

3. In the construction defined in claim 2,

foregoing, the thermostatic field 'dellector beingin the form of a quadrant arm mounted by one' end on the rotor andy having the other end free for movement toward and from the magnet poles.

4. In the construction defined in claim 2 foregoing, the thermostatic eld deflecting member being arcuate in approximate conformity to the magnet path of rotation, secured at one extremity to the rotor and at the other end free to move under lexure and intermediatel stopped as' to movement for carrying the ree end toward and from the magnet oles, and means for adjusting the interme iate stop. j

5. In the construction defined` in claim 2 foregoing, r the thermostatic field delector being a spring bar arcuatein form-in approximate conformity to 'the magnet path of rotation, secured at one end of its arc form to the rotor, and at the other end free t0 move under lexure, and an intermediate s top. within the range of its resilientreac- ANDREW c. Woon'.

Illinois, this 30th I have hereunto 

